In recent years, heat treatments by which heat is applied to tumors in examined subjects so as to cause thermal necrosis have been put into practical use for the purpose of treating enlargement of the prostate gland, cancer, and the like. To perform such heat treatments more efficiently, it is necessary to understand the position of the heated region and the temperature of the heated region in each examined subject.
To understand the position and the temperature of the heated region, one of the methods that have been tried is to take a longitudinal-relaxation-period-weighted image of the body tissues of the examined subject and to measure changes in the temperature based on changes in the image, while utilizing the characteristic where the relaxation period of a magnetic resonance signal has a temperature dependency (see, for example, Japanese Patent Application Laid-open No. 2001-231762).
To perform a heat treatment by using the magnetic resonance diagnostic apparatus described above, it is necessary to provide, separately from each other, the magnetic resonance diagnostic apparatus used for measuring the changes in the temperature and the heating apparatus used for performing the heat treatment.
When the magnetic resonance diagnostic apparatus and the heating apparatus are provided in locations distant from each other, it is necessary to repeatedly perform the following steps: first, the examined subject is brought to the heating apparatus so that the heating process can be performed thereon; and subsequently, the examined subject is brought to an image taking position of the magnetic resonance diagnostic apparatus so that the temperature can be measured. In this situation, because it is not possible to perform the heating process and the temperature measuring process at the same time, it is difficult to accurately understand the changes in the temperature caused by the heating process.
Alternatively, another method is also possible by which a small-sized heating apparatus that can be inserted into the heated region of the examined subject is structured, so that a heat treatment can be performed while the examined subject is placed in the image taking position of the magnetic resonance diagnostic apparatus. This method, however, is highly invasive and causes a large burden on the examined subject because the heating apparatus needs to be inserted into the examined subject.